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https://dev.mysql.com/doc/refman/5.7/en/replication-features-optimizer.html
It is possible for the data on the source and replica to become different if a statement is written in such a way that the data modification is nondeterministic; that is, left up the query optimizer. (In general, this is not a good practice, even ...
https://dev.mysql.com/doc/refman/5.7/en/using-explain.html
See Section 8.2.2.1, “Optimizing Subqueries, Derived Tables, and View References with Semijoin Transformations”. The EXPLAIN statement provides information about how MySQL executes statements: EXPLAIN works with SELECT, DELETE, INSERT, REPLACE, ...
https://dev.mysql.com/doc/refman/5.7/en/examples.html
Here are examples of how to solve some common problems with MySQL. Some of the examples use the table shop to hold the price of each article (item number) for certain traders (dealers). Supposing that each trader has a single fixed price per ...
https://dev.mysql.com/doc/refman/5.7/en/explain-output.html
select_type Value JSON Name Meaning SIMPLE None Simple SELECT (not using UNION or subqueries) PRIMARY None Outermost SELECT UNION None Second or later SELECT statement in a UNION DEPENDENT UNION dependent (true) Second or later SELECT statement in a ... The EXPLAIN statement provides information about how MySQL executes ...
https://dev.mysql.com/doc/refman/5.7/en/optimizer-hints.html
Changes to this variable affect execution of all subsequent queries; to affect one query differently from another, it is necessary to change optimizer_switch before each one. For more information about these optimizations, see Section 8.2.2, ... One ...
https://dev.mysql.com/doc/refman/5.7/en/server-status-variables.html
If this value is high, it is a good indication that your tables are properly indexed for your queries. This value is high if you are doing a lot of queries that require sorting of the result. You probably have a lot of queries that require MySQL to ... The MySQL server maintains many status variables that provide information about its ...
https://dev.mysql.com/doc/refman/5.7/en/mysqlslap.html
Run all the load statements, then run all the queries in the query file with five clients (five times each): mysqlslap --concurrency=5 --iterations=5 --query=query.sql --create=create.sql --delimiter=";" mysqlslap supports the following options, ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html
Normal operations can continue while the hash table is emptied, and executing queries that were using the hash table access the index B-trees directly instead. innodb_api_trx_level Command-Line Format --innodb-api-trx-level=# System Variable ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-information-schema-examples.html
Note There may be inconsistencies between queries shown in the INFORMATION_SCHEMA PROCESSLIST and INNODB_TRX tables. Identifying Blocking Transactions It is sometimes helpful to identify which transaction blocks another. The tables that contain ...
https://dev.mysql.com/doc/refman/5.7/en/order-by-optimization.html
Assuming that there is an index on (key_part1, key_part2), the following queries may use the index to resolve the ORDER BY part. queries as if you also included ORDER BY col1, col2, ... Some types of queries are particularly suited to completely ...